/Engine/Source/Runtime/Engine/Public/ISMPartition/ISMPartitionActor.h
int32 GetISMInstanceIndex ( const [FISMClientHandle](API\Runtime\Engine\ISMPartition\FISMClientHandle) & Handle, const [UInstancedStaticMeshComponent](API\Runtime\Engine\Components\UInstancedStaticMeshComponent) * ISMComponent, int32 ComponentIndex ) const